This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The core is for the production and cryopreservation of virus stocks to be used by NIH funded investigators. The core is designed to avoid duplication of effort and cost in the preparation of virus stocks, particularly SIV and SHIV. The viral stocks were all quantified by TCID50 in the appropriate cell line. Thus, the core prevents the unnecessary duplication of effort and expense among investigators at the TNPRC. The core maintains records on the pedigree of all virus stocks. In 2010, 61 virus stocks were stored in Liquid Nitrogen and 44 in ultra low temperature freezers at the TNPRC. An Excel database with details on the frozen stocks was maintained and includes: date frozen, titration date, TCID50, the number of vials of each virus and the exact storage location. In the past year, the core has supplied 46 vials of different viral stocks. Of those stocks, 31 vials were prepared in 2010 as a result of specific investigator requests. Several stocks of three different viruses were also prepared and/or added to the core in this year. They include RT-SHIV, SIV.SIVhybrid and HIV-2. Over the past year, 1 Rabbitpox virus challenge stock was stored in Liquid Nitrogen at the TNPRC. This program represents expansion of the core to include other viruses at the TNPRC. Rabbitpox is part of a biodefense research program headed by Dr. Chad Roy also in the Division of Microbiology at the TNPRC.